Simulation models of obesity: a review of the literature and implications for research and policy

Simulation models (SMs) combine information from a variety of sources to provide a useful tool for examining how the effects of obesity unfold over time and impact population health. SMs can aid in the understanding of the complex interaction of the drivers of diet and activity and their relation to health outcomes. As emphasized in a recently released report of the Institute or Medicine, SMs can be especially useful for considering the potential impact of an array of policies that will be required to tackle the obesity problem. The purpose of this paper is to present an overview of existing SMs for obesity. First, a background section introduces the different types of models, explains how models are constructed, shows the utility of SMs and discusses their strengths and weaknesses. Using these typologies, we then briefly review extant obesity SMs. We categorize these models according to their focus: health and economic outcomes, trends in obesity as a function of past trends, physiologically based behavioural models, environmental contributors to obesity and policy interventions. Finally, we suggest directions for future research.

Telomere length in relation to insulin resistance, inflammation and obesity among Arab youth

AIM

The aim of this study was to determine the associations of telomere length to markers of obesity, insulin resistance and inflammation in Saudi children.

METHODS

A total of 69 boys and 79 girls, aged 5-12 years, participated in this cross-sectional study. Anthropometrics were measured. Serum glucose and lipid profile were measured using routine laboratory methods. Serum insulin, leptin, adiponectin, resistin, tumour necrosis factor-alpha and active plasminogen activator inhibitor 1 were quantified using customized multiplex assay kits. C-reactive protein and angiotensin II were quantified using ELISA. Leucocyte telomere length was examined by quantitative real time PCR utilizing IQ cycler.

RESULTS

Mean telomere length was significantly shorter in obese boys compared with their lean counterparts (p = 0.049), not in girls. It was not associated to insulin resistance, adipocytokines and markers of inflammation. In girls, the significant predictor of telomere length was waist circumference, explaining 24% of variance (p = 0.041) while in boys, systolic blood pressure explained 84% of the variance (p = 0.01).

CONCLUSION

Childhood obesity in boys corresponds to shorter leucocyte telomere length which is not evident in girls. The association of leucocyte telomere length to blood pressure and waist circumference in children suggests clinical implications as to the contribution of these parameters in premature ageing.

Eating patterns and dietary composition in relation to BMI in younger and older adults

OBJECTIVE

To compare relative associations of eating patterns and dietary composition with body mass index (BMI) in younger (aged 20-59 years, n=1792) and older (aged 60-90 years, n=893) participants in the Continuing Survey of Food Intakes by Individuals, collected 1994-1996.

METHODS

Data from two 24-h dietary recalls from individuals reporting physiologically plausible energy intake (within +/-22% of predicted energy requirements, based on previously published methods) were used.

RESULTS

Mean reported energy intake was 96 and 95% of predicted energy requirements in younger and older subjects, respectively. Older subjects were less likely than younger subjects to skip a meal, but snacking was common in both age groups. Fiber density was significantly higher in the older group. A higher BMI in both age groups was associated with a higher total daily energy intake, and higher energy intakes at all eating occasions. In both age groups, eating frequency was positively associated with energy intake, and eating more than three times a day was associated with being overweight or obese. In the younger group but not the older group, a lower fiber density coupled with higher percentage of energy from fat was independently associated with having a higher BMI.

CONCLUSIONS

While no one eating occasion contributes more than any other to excess adiposity, eating more often than three times a day may play a role in overweight and obesity in both younger and older persons. A reduced satiety response to dietary fiber in addition to lower energy expenditure may potentially further contribute to weight gain in older persons.